This invention relates to a process for reducing sulfur emissions which are an undesirable byproduct of a cement manufacturing process. This invention has particular utility in a fluid bed cement manufacturing process.
Sulfur is introduced to the fluid bed cement process primarily by the various forms (sulfides/sulfates) present in the cement raw materials and, secondly, by the sulfur fraction found in most fossil and waste fuels. A general sulfur balance shows that sulfur departs the process in three streams: (1) calcium sulfate and non-volatilized alkali sulfates in the cement product, (2) alkali sulfate/chloride solids collected by the particulate filtration system and (3) as SO.sub.2 emitted to the atmosphere.
Processing cement plant kiln dusts also pose an emission problem as they contain relatively high concentrations of alkali sulfates and calcium sulfates. Excess sulfur generated leaves the system as gaseous SO.sub.2 emissions. Typically, this level of SO.sub.2 emissions at the stack is significantly greater than that generated processing cement raw mix.
Previously, options were not available to economically provide the degree of SO.sub.2 control in cement forming processes utilizing either cement raw mix and/or cement kiln dust as a starting material in a manner suitable to meet stringent EPA requirements, particularly in the case of the fluid bed processing of cement kiln dusts. According to the present invention, there is described an effective method to reduce SO.sub.2 emission levels from the fluid bed cement process, both in the processing of standard grey cements, white cements and cement kiln dusts.